Drug interactions
Lofexidine + Thioridazine
Severity: Major
Lofexidine and Thioridazine: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Lofexidine is metabolized partly by CYP2D6, which thioridazine inhibits, so lofexidine exposure may rise. Both drugs prolong the QT interval, and lofexidine causes bradycardia, hypotension and sedation. The combination raises the risk of torsades de pointes and excessive sedation.
What this interaction means in plain words
Lofexidine and Thioridazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Lofexidine belongs to Central Nervous System; Thioridazine belongs to Central Nervous System.
Why it happens
CYP2D6 inhibition by thioridazine increases lofexidine levels, with additive QT prolongation, bradycardia and CNS depression.
What to do
Avoid the combination if possible. If used, monitor ECG, heart rate and blood pressure, correct electrolytes and consider lowering the lofexidine dose.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Other interactions of Lofexidine
- Adagrasib + Lofexidine Major
- Alfuzosin + Lofexidine Major
- Amiodarone + Lofexidine Major
- Amisulpride + Lofexidine Major
- Anagrelide + Lofexidine Major
- Apomorphine + Lofexidine Major
Frequently asked questions
Can I take Lofexidine with Thioridazine?
MediHelp rates the interaction as major. Lofexidine and Thioridazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Lofexidine is metabolized partly by CYP2D6, which thioridazine inhibits, so lofexidine exposure may rise. Both drugs prolong the QT interval, and lofexidine causes bradycardia, hypotension and sedation. The combination raises the risk of torsades de pointes and excessive sedation.
How serious is the interaction between Lofexidine and Thioridazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible. If used, monitor ECG, heart rate and blood pressure, correct electrolytes and consider lowering the lofexidine dose.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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